Squamous cell carcinoma in situ of the vagina and cervix after intrauterine DES exposure.

Two patients exposed in utero to maternal DES ingestion presented with adenosis. Each developed intraepithelial neoplasia in an area of active metaplastic change. The question is raised whether a continuum exists beginning with DES exposure and proceeding through the occurrence of adenosis and active squamous metaplasia to dysplastic alteration and finally squamous neoplasia. Since the cytologic smear is negative in 50% of cases during the dysplastic phase, it is recommened that all cases of adenosis be followed by colposcopy.